Addition of Partial Envelope Domain II into Envelope Domain III of Dengue Virus Antigen Potentiates the Induction of Virus-Neutralizing Antibodies and Induces Protective Immunity

Abstract

Dengue virus (DENV) comprises four serotypes in the family Flaviviridae and is a causative agent of dengue-related diseases, including dengue fever. Dengue fever is generally a self-limited febrile illness. However, secondary infection of patients with a suboptimal antibody (Ab) response provokes life-threatening severe dengue hemorrhagic fever or dengue shock syndrome. To develop a potent candidate subunit vaccine against DENV infection, we developed the EDII-cEDIII antigen, which contains partial envelope domain II (EDII) including the fusion loop and BC loop epitopes together with consensus envelope domain III (cEDIII) of all four serotypes of DENV. We purified Ab from mice after immunization with EDII-cEDIII or cEDIII and compared their virus neutralization and Ab-dependent enhancement of DENV infection. Anti-EDII-cEDIII Ab showed stronger neutralizing activity and lower Ab-dependent peak enhancement of DENV infection compared with anti-cEDIII Ab. Following injection of Ab-treated DENV into AG129 mice, anti-EDII-cEDIII Ab ameliorated DENV infection in tissues with primary and secondary infection more effectively than anti-cEDIII Ab. In addition, anti-EDII-cEDIII Ab protected against DENV1, 2, and 4 challenge. We conclude that EDII-cEDIII induces neutralizing and protective Abs, and thus, shows promise as a candidate subunit vaccine for DENV infection.

Plant‐made dengue virus‐like particles produced by co‐expression of structural and non‐structural proteins induce a humoral immune response in mice

“…For further studies, it would be interesting to directly compare the neutralizing antibody response of DENV1 VLPs with E‐DIII displaying hepatitis B particles, because the production of neutralizing antibodies in humans is not limited to the EIII region but rather involves the quaternary structures formed by E protein multimers (de Alwis et al ., 2012; Wahala et al ., 2009). Furthermore, the extension of the EIII domain subunit with a part of the E domain II led to improved neutralizing antibody titre (Park et al ., 2020), indicating that the use of VLPs displaying the whole E protein is likely to be the most suitable DENV vaccine strategy, provided that prM cleavage and maturation of VLPs can be achieved to avoid the production of non‐neutralizing, but enhancing antibodies. In fact, we attempted to display the entire DENV1 E ectodomain on the surface of tandem hepatitis B core particles to compare this external antigen display strategy with our DENV1 VLPs, but we were unable to produce such full‐length E‐displaying HBcAg CLPs.…”

Enzymatic bioconversion of ginseng powder increases the content of minor ginsenosides and potentiates immunostimulatory activity

“…RNA was extracted using the Easy-BLUE Total RNA extraction kit (Intron Biotechnology, Sungnam, Korea) and converted into cDNA using a reverse-transcription reaction system (Promega, Fitchburg, WI, USA). Quantitative real-time PCR analyses were performed using SsoAdvanced Universal SYBR Green Supermix (Bio-Rad Laboratories, Hercules, CA, USA) with the CFX Connect Real-Time PCR Detection System (Bio-Rad), as described previously [ 17 ]. Gene expression was normalized against a β-actin internal control gene.…”

Current Flavivirus Research Important for Vaccine Development

“…In this Issue, Park et al outlines a candidate subunit vaccine based on eliciting a strong neutralizing antibody response against E DIII. This vaccine was developed to combat all four DENV serotypes by combining two subunits: partial envelope domain II and consensus envelope domain III (cEDIII) [ 10 ]. The authors found that an antibody purified from mice following immunization with this combined candidate vaccine was strongly neutralizing compared to their single subunit vaccine containing only cEDIII, with limited non-neutralizing antigen-specific antibody [ 10 ].…”

“…This vaccine was developed to combat all four DENV serotypes by combining two subunits: partial envelope domain II and consensus envelope domain III (cEDIII) [ 10 ]. The authors found that an antibody purified from mice following immunization with this combined candidate vaccine was strongly neutralizing compared to their single subunit vaccine containing only cEDIII, with limited non-neutralizing antigen-specific antibody [ 10 ]. In addition, this combined subunit vaccine was able to reduce DENV titers in several tissues when compared to the single subunit vaccine, and conferred protection against DENV1, 2 and 4 in murine challenge models, thus showing promise as a candidate DENV subunit vaccine [ 10 ].…”

“…The authors found that an antibody purified from mice following immunization with this combined candidate vaccine was strongly neutralizing compared to their single subunit vaccine containing only cEDIII, with limited non-neutralizing antigen-specific antibody [ 10 ]. In addition, this combined subunit vaccine was able to reduce DENV titers in several tissues when compared to the single subunit vaccine, and conferred protection against DENV1, 2 and 4 in murine challenge models, thus showing promise as a candidate DENV subunit vaccine [ 10 ]. Similarly, Tremblay et al highlights how the discovery that flavivirus vRNA 2′- O -methylation enables mimicry of cellular mRNAs has been instrumental in reverse genetics studies to improve DENV vaccine design [ 11 ].…”